1. Field
This invention is directed to a means and method of solid phase radioimmunoassay and particularly to a solid scintillating immunoadsorbent cell capable of selectively retaining labeled materials in close proximity to a phosphor.
2. State of the Art
Radioimmunoassay, also referred to as radioimmune assay, competitive radioassay, radiostereoassay or immune radiometric analysis, is a known analytical technique for quantitatively measuring specific proteins, polypeptides and biological agents such as insulin, hormones, enzymes, antigens and the like by the use of radioactive isotopes. Specifically, radioimmunoassay is used for testing of both clinical and experimental samples for viral, physiological and bacterial diseases, polypeptides and steroid hormones, drugs, pesticides and the like. The method of assay relies on the antibodies' specific ability to bind, without preference, a specific antigen (or hapten) whether the antigen be labeled or unlabeled. By combining a known amount of labeled antigen with an unknown amount of unlabeled antigen and by adding this mixture to a specific antibody, a certain percentage of the labeled and unlabeled antigen will be bound to the antibodies. The percent of bound labeled antigen corresponds to the concentration of unknown, unlabeled antigen present in the mixture. The antibody-bound labeled and unlabeled antigens are separated from the unbound mixture and the radioactivity in one or both of these fractions is counted. To facilitate the radioactivity count, a liquid scintillator cocktail or solution is added to one or both of the separated fractions and placed in close proximity to a scintillator for a radioactive count. The radioactive energy released from the labeled antigens externally excites the scintillator causing bursts of light emissions which are then detected and measured. In instances where the radioactive material emits energy of suitable intensity, e.g., radioactive iodine, the phosphor may be eliminated or incorporated in the counting mechanism.
When the scintillator, the antibodies and the sample mixture of labeled and unlabeled antigens are carried by and combined in a solvent, the scintillator cannot be readily recovered for reuse nor can the antigen be readily separated from the antibodies, thus preventing the antigens to be reused for additional study and/or testing and must therefore be discarded.
Another problem is that when a solvent vehicle called the liquid scintillation "cocktail" is employed in a fully or partially automated radioimmunoassay system, the system requires a complicated, solvent resistant plumbing arrangement to pump and accurately introduce the solvent into the system. Another major problem is that the procedures of reacting the antigens and antibodies, separating the bound antigens from the unbound and measuring the radioactivity of these fractions are usually done as separate and sequential operations which are more time consuming than if they were combined into a single step operation. Even when all of these sequential operations are automated, the time required in moving the materials around and measuring radioactivity is undesirably more than if the automated system performed these operations in one place.